How much do double blades help???

I have been considering the double blade set-up and I'd like to know how much it helps with the quality of the cut AND how much it helps with MULCHING. I mulch all my properties and eliminating clumping and missed grass is a must. Getting a wider mower won't help if I am double cutting haha.

So for those who run double blades or know a lot about it please tell me what double blades help with the most. Thanks.